According to the website, there is no way for new Google Glass users to tweet photos taken using their device because the Twitter app has disappeared.

Reddit user pete716, one of the "Glass explorers" given early access to the device, posted about the removal of the official Twitter app from Google Glass:

According to Glass support Twitter is no longer developing their Glass app. This was one of my favorite and most used apps on Glass. If you remove Twitter from your Glass it disappears from Glassware and there is no option to reinstall it.

It's not clear why Twitter has decided not to support the product anymore, but it does mean that until a third-party developer comes along and makes a new Twitter app for Google Glass, these devices users are stuck.